Telephone-exchange system



April 14,-1925.

' C. W. KECKLER TELEPHONE EXCHANGE SYSTEM .Filed Dec. 6. 1919 PatentedApr. 14, 1925.

UNITED STATES PATENT OFFICE.

CHARLES W. KECKLER, 0F NEWARK, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

' TELEPHONE-EXCHANGE SYSTEM.

Application filed December 6, 1919.

To all whom it may concern:

Be it known that 1, CHARLES W. KEGKLER, a citizen of the United States,residing at Newark. in the county of Essex, State of New Jersey, haveinvented certain new, and use ful Improvements in Telephone-ExchangeSystems, of which the following is a full, clear, concise, and exactdescription.

This invention relates to telephone ex change systems and moreparticularly to cir- I cuit arrangements at a manual private branchexchange where such an exchange is employed in connection with a mainexchange of thecommonbattery type. I

An object of the invention is to provide improved signaling means forsuch systems,

and to. avoid the tying up of trunks extending between the privatebranch exchange and the distant exchange in cases of slow disconnect onthe part of the operator. I I Another object of the invention is to pro-.vide for instantaneous recall on the part of the subscriber at theprivate branch exchange or the distantoffice.

A further object of thein'vention is to )revent ringing current fromfalsely signaling the connected subscriber at the private branchexchange in cases of a second call from thedistant oflice for theprivate branch exchange prior to disconnection by the operator. I I I II In the present embodiment of the invention the circuit arrangementsare such that the, subscriber at the private branch exchange controlsthe release of a trunk lead- I ing to the dist-ant o-ifice.

More specifically restoration of ther CQlVGlftO, the switchhookofthesubscriber at. the private branch exchange, after completion ofconversation with a subscriber at the distant office, opens the lineloop thereby causing a supervisory lamp to be actuated and the automaticswitches at a distant oflice to be-Teleased. Restoration of the receiveralsocausesaswitching relay in the'trunk circuit at the private branchexchange to operate thereby connecting the line. signal to the trunk andopening up the trunk conductors, which-enables the operator to again besignaled over said trunk and prevents ringing current from passing tothe con- Serial No. 343,003.

nected station in case of a slow disconnect.

A further feature is the provision of means whereby, prior todisconnecting by the operator, the subscriber at the private branchexchange may either signal the operator indicating that a connectionwith another station of the private branch exchange is desired or he maywithout the aid of the operator call a subscriber at the distant oflice,in the latter case a supervisory relay being actuated at the privatebranch exchange thus indicating to the operator thereat that the lineand trunk connected thereto are busy.

For a more complete understanding of this invention reference should behad to the I following description and to the accompanying drawing whichillustrates one embodiment thereof. Vhile the invention is shown inconnection with an automatic exchange, obviously it could be employedwith a manual common battery exchange.

There is shown in the drawing a telephone line A terminating in anautomatic exchange. By meansof an impulse sender S and automaticswitching apparatus, such as a line finder F, selector L and connectorC, diagrammatically indicated, the subscriber A may select a trunk. suchas T extending from the automatic exchange to the manual private branchexchange. The apparatus shown to the left of the dotted line OO islocated at the automatic exchange and that to the right thereof at themanual exchange. At the manual exchange, a signaling means, a switchingrelay and a jack in which the trunk terminates are provided. By means ofthe link circuit B the calling line A may be extended to any stationsuch as D terminating in a jack at the private branch exchange. I I

The nature of this invention is such that it is believed that a clearunderstanding thereof will be obtained from a description of theoperation of the system shown in the drawing. and it will be sodescribed.

Itwill be assumed that a subscriber at substation A in the automaticexchange desires a connection with a subscriber D terminating in amanual exchange. The subscriber at substation A will therefore re-v nerand ringing current is sent over the.

conductors 12, 13 of the trunk T to the manual exchange to actuate asignal thereat, the path therefor beingas follows: ground, third contactof side switch and its brush 10, conductor 12, outer left-hand armatureand back contact 'of relay 21, lefthand winding of relay 22, condenser23,

. conductor 13, side switch brush 11 and its third contact, winding ofrelay 24, and armature. and front contact of relay 25, (which isenergized in position 3 of the side switch brushes) to source of ringingcurrent 26. Relay 22, upon'energization establishes alocking circuit foritself including itsright-hand winding, front contact and armature andthe back contact and inner left-hand armature of relay 21 and also com-1 pletes a circuit for the line si nal 20 from battery, lamp 20, frontcontact and armature of relay 22 andback contact and innerleft-handarmature of relay 21 to ground.

In response to the signal, the operator inserts the plug 28 of the linkcircuit '15 into jack29 of the trunk circuit T. Relay 21 of the trunkcircuit T and relay 30 of the link circuit B are thereupon energizedover a circuit from grounded battery, winding of relay, 21. sleeves ofvjack 29 and plug 28, left-hand normal contact of relay 31 and winding ofrelay 30 to ground. Relay- 21 in energizing disconnects the ringingrelay 22. from the trunk circuit and interrupts the I circuit for thelamp 20 at its left-hand armatures and at its right-hand armaturesconnects the trunk circuit through to, the link circuit B. Relay 30 ofthe link circuit B at. its inner left-hand armature and front contactcompletes a bridging circuit, including the left-hand inner armature andback contact of relay 44 and the wi'dings' 32 and 33 of a retardationcoil, across the talking conductors of the cord circuit thereby caus- 1ingringing relay 24 in the connector circuit G to energize to trip themachine, ringing andmove the side switch brushes of the conneotorintoposition 4 in the manner well known.

The operator thenactuates the listening key 35 thus connecting hertelephone set (not shown) incircuitv so that she may converse with thecalling subscriber, and having as certained that station D is desired,the operator inserts calling plug 40 of the link circuit into jack 41,in which the line leading to station D terminates.- Supervisory lamp 42lights and the line cut-off relay 43 is energized over a circuitextending from grounded battery, lamp 42, back contact and right-handarmature of relay 44, back contact and armature of supervisory relay 45,sleeves of plug 40 and jack 41 and winding of relay 43 to ground; Theoperator will then actuate ringing key 46 of the link circuit 13 tosignalstation D in the usual manner.

Upon response of the called subscriber, a

path for the talking current for station D may be traced as follows:ground, left-hand winding of relay 5 of the connector C, side switchbrush 10 in its fourth position, conductor 12, front contact and outerrighthand armature of relay 21, tip of jack 29 and of plug 28, uppernormal contacts of ringing key 50, right-hand normal contacts lowernormal contacts of. ringing. key 50,

ringof plug 28, ring of jack 29, right-hand inner armature and. frontcontact of relay 21, conductor 13, side switch brush 1.1 in its fourthposition, and right-hand winding of relay 5 of the connector C togrounded battery. Suflicient current. flows through supervisory relay 45to cause its energization although up until the time that relay 45 isenergized, the retardation coil windings are bridged across the linkcircuit. Relay 45 attracts its armature and in so doing causes thesupervisory lamp 42 to befextinguished and the holding bridge across thetalking conductors of the link circuit B to be disabled. Relay 44, whichinterruptstlie holding bridge at its inner left-hand ar'ma ture and backcontact, is energized over the following paths: grounded battery, outer.left-hand armature and front contact of relay 30,. winding of relay 44,front contact and armature of relay 45, sleeve of plug 40, sleeve ofjack 41, and winding of relay 43 to ground. Relay 44 is he'ldlocked upthrough its outer left-hand armature and front contact and the normalcontact of listeningkey 35 through resistance coil 27, to ground. p

At the conclusion of conversation subscriber D restores the receiver to.the switchhook, thus opening up the loop for relay 5 of theconnectorswitch C, which will cause the restoration of the switches inthe automatic exchange in the manner well known. Trunk circuit T maythen be selected by another connector causing trunk signal 20 to lighteven though the plug. 28 is not removed from jack 29 immediately, as inthe case of a slow disconnect, in a manner hereinafter described;TSupervisory relay 45' is deenergized upon the restoration ofthereceiver of station D to its switchh'ook, thereby causingenergization of relay 31 over a path extending from grounded battery,winding of relay 3l, front contact and right-handarmature of relay 44,back-contact and armature of supervisory relay 45., sleeve of plug 40,sleeve of jack 41, and winding of relay 43 to ground. Relay 31, uponenergization, establishes at itsrighthand armature and front contact acircuit for supervisory lamp 42 causing it to light to indicate to theoperator that conversation is completed. At the left-hand armature andnormal contact of relay 31, the circuit for relay 21 is interrupted,thus opening up the talking conductors of the trunk T, and againbridging the ringing relay .22 across the trunk. 1

In case another call comes in over'the trunk from. the ..aut0maticexchange, before the operator has disconnected, ringing relay 22 willagain be energized causing the line signal to light. Ringingcurrent'will be prevented from passing through to the stationD since thetalking conductors of the trunk are open at the contacts of relay 21.VVhenrelay-31 was energized a circuit for relay 30 was maintained thoughgrounded battery, resistance 60, and the left alternate contacts ofrelay 31, which are of themakebefore-break type. i i

Assuming that a second 'call has arrived over the trunk circuit T, relay22 will be energized as heretofore described and-the trunk lamp 20 willlight. The operator observing the signal actuates'listening key 35 andin so doing interrupts at its normal contact the locking circuit forrelay 44. Relay 44, uponv deenergization, interrupts at its right-handarmature and contact, the circuit for relay 31 and at its innerleft-hand armature and back contact restores the bridge across thetalking conductors of link circuit B. Relay 31 in deenergizing againcompletes a circuit at its left-hand armature and normal contacts forrelay 21,'which,

upon energization, disconnects ringing relay 22 and signal 20 from thetrunk circuit B, and reestablishes the continuity ofthetalkingconductors of the trunk circuit. The bridge across the linkcircuit B tripsthe machine ringing as before and causes the side switchbrushesto move from position 3 to p0sition4, thus enabling the operatorto converse with the calling subscriber, In case substation D is againdesired, the operator actuates the ringing key 46 to signal stationD,-or-. in' case some other station is desired, plug 40 is removedfro1n..jack. 41

and inserted in:,the jack in which the desired line terminates. Uponcompletion of conuver'sation supervisory lamp42 lights, as beforedescribed, whereupon the operator removes the plugs from theirassociated jacks and all relays are restored to normal.

Assume that substation D desires to make a call or gain the attention ofthe operator prior to disconnection. The supervisory lamp 42 of the cordcircuit maybe flashed in responseito actuations of the switchhook atstation D. Removal of the receiver at station D prior to disconnection,causes energization ofsupervisory relay 45 over the following'path:ground, resistance 16 of the trunk circuit T, tip of jack 2!) and ofplug 28, upper normal contacts of ringing key 50, right-hand normalcontacts of. dialing key 51, upper normal contacts of ringing key 46,tip of plug 40 and of jack 41 over the loop of station 1), ring of jack41 and of plug 40, lower. normal contacts of ringing key 46, inductivewinding of supervisory relay 45 and non-inductive winding 52 thereof,and right-hand armature and front contact 'ofrelay 30 in parallel,left-hand normal contacts of dialing key 51, lower normal contacts ofringing key 50, ring of plug 28 and of jack 29, inner right-handarmature and back contact of relay 21, and

resistance 15 to grounded battery. Attraction of the armature of. relay45 interrupts the circuit for supervisory lamp 42. The operator notingthe supervisory signal actuates listening key 35 and converses withstation D, and in case another station at the manualexchange is desired,plug 28 will he removed from jack 29 and inserted in the jack. to whichthe desired line is connected.

Supposing on the other hand that prior to disconnection station Ddesires to dial a subscriber at the: automatic exchange. 11 will beremembered that prior to removal of plugs 28 and 40 from theirassociated iacks, and after the-subscriber at station D has hung up,relays 21 and 45 are deenergized and relays 30, 44 and 31 are ener ized.Removal-of the receiver atstation D from the switchhook energizessupervisory relay. 15, which attracts its armature. thereby interruptingatits hack contact the circuit for lamp 42 causing it tobe extinguishedand indicating to the operator that the cord cir-. cnit is in use. wAttraction of the armature of relay 45 also interri'lpted at the backcontact thereof; the circuit for relay 31 causing it to deenergize.Deenergization of relay 31 reestablishes at its left-hand armature andnormal-contact, the circuit for relay 21. causing the latter toenergize,.thus extending the line of station D over the trunk circuit T.to' the automatic exchange, wlrere the trunk terminatingat theconnector C may be multiplied togthe 'line or trunk finder schematicallyrepresented onthe drawing by the rectangle X.- The. subscriber atstation D may now actuatehis dial E to select the number desired in themanner well-known.

With each interruption in the linecircuit' of station-D, relay willdeenergizeand at its armature and back contact close a" circuit forrelay 31. This relay" is of theslow-to-operate type, however, and willnot follow-the interruptions in; the: .line circuit; To indi catethat-relay 3l=is of the. slow' topperate type, arrows: pointing inithe'direction in which the armatures slowlymove are shown on thedrawing.

Upon completion "of conversation, restoration to the switchhook-lof thereceiver? at" sta tion D will open the line circuit, causedeenergizationof supervisory" relay 45 and the lighting of lamp 42,Armature of relay +5 in retracting again completes the circuit for relay31-, which, upon energizing; interrupts the circuit for relay 21therebyagain connectin g the alternating current bridge across the trunkand interrupting the continuity of the trunk conductors; The operator,noting' that the supervisory signal 4-2- is lit, will removethe plugsfrom their associated jacks, and all relayswill be restored to-normal;

A calling dial 61 is provided for the cord circuit by means of which theoperator may select forthe calling-subscriber D, a line terminating inthe-automatic exchange. Resistances 62and 63 connectedto battery andground, respectively, supply current to the line of subscriber I.) whendialing key 51 is actuated, so'that' the subscriber may still controlthe supervisory signal. Since such arrangements-are well known and thisforms no part of the present invention, a description of suchanoperation is deemedunnecessary.

What is claimed is:-

1. In a telephone exchange-system, aman'- ual switchboard, a trunk line"including a pair of normallydiscontinuoustalking (onductors terminatingthereat, an: alternating current bridge normally connected-to" saidtalking conductors, a subscribers line terminating at" said switchboard,a link i circuit for connecting-said trunkline'to said subscribers'line, a relay in said trunkcircuit adapteduponenergization to interruptsaid alternating current bridge and establish" the continuity ofsaid'talking conductor-s, means under'thecontrol of the operatonfor energizing said relay, and means-under the con trol of the subscriber fordeenergizing'said relay. 7

2. Ina telephone exchange system, an automatic telephone: exchange,callingsub scribersline terminating thereat, a manual telephoneexchange, a calledisubscribefls line terminating thereat, meansincluding automatic switches and a trunk circuit for extendingconnection from c said calling to said called line, a-link circuit atsaidmanual exchange forextendingsaid calling to said calledline,signaling means associated with said trunk circuit, means u'nd'er thecontrol of the operator for dlsconnectmg and reconnecting; saidsignaling means tonsaidcontinuity of the talking conductors of saidtrunk circuit and to disconnect said signaling. means, andupondeenergization to restore said: trunk and said signaling means tonormal condition, a" subseribersline, a link circuit for connectingsaid' trunk cir cuit with said subscribers line' and means controlled bythe subscriber for energizing or deenergizing said switching relay;-

4'; In a-telephone exchange system,-aman-' ual exchange, a subscribersline terminating at saidmanualexchange, a trunk circuit extending to anautomatic exchange terminatingzat said manual exchange, a link circuitat said manual exchangefor completing a-connectionreceived from saidautomatic exchange for a subscriber at said manual exchange, andmeanscontrolled by'the subscriberat said manual exchange-for rendering;the trunk selectable immediately upon completion of conversation:

5: In combination with a trunk circuit and acord circuit for extending acall from a subscriber-at an automatic-exchange to a subscriber at amanual exchange, means whereby when the called subscriber at the manualexchange hangs upnfter completion of" conversation, the'trunk-circuit isavailable for arecall or asecond call over said trunk.

'6. In a telephone exchange system, an automaticexchange, a calling.subscribers line terminating thereat, a manual exchange, a called-subscriberis line terminatingithereat, meansincluding a: trunk line forextending said calling: line to said. mamialxexchange, a: link circuitat said manual exchange for-extending" said trunk line to said =c'al1ed'line, means under the con trol of'the calledisubscriber; for releasingthe switches at said automatic exchange, and means: whereby the" calledsubscriber may immediately "after having releasedsaid switches; initiatea call over said link circuit and saidtrunk circuit for an automaticsubscriber without the aid of theopera tor.

7.111 a telephone exchange system, an automatic exchange, a callingsubscriber s line teri'ninatingthereat, a manual exchange, a calledsubscribers line terminating thereat, means including a trunk circuitfor extending a call from said calling subscriber to said manualexchange, a link circuit at said manual exchange for extending saidtrunk circuit to said called line, means under the control of the calledsubscriber for releasing the switches at said automatic exchange, meansfor enabling the called subscriber to initiate a call for a subscriberat said automatic exchange immediately after having released theswitches, and supervisory means in the link circuit actuated in responseto the initiation of said call for indicating to the operator that saidlink circuit is in use.

8. In a telephone exchange system, an automatic telephone exchange, acalling subscribers line terminating thereat, a manual telephoneexchange, a called subscribers line terminating thereat, a trunk circuitextending between the two exchanges, switching apparatus controlling thecontinuity of the trunk line and a line signaling device associated withsaid trunk circuit at the manual exchange, the signaling deviceresponding to a call initiated by the calling subscriber, a

link circuit at the manual exchange for connecting said trunk to theline of the called subscriber, means for disabling the signaling deviceand for actuating the switching apparatus to receive the incoming callupon the connection of the link circuit with the trunk circuit, meanscontrolled by the called subscriber for restoring said switchingapparatus and the signaling device to normal association with said trunkcircuit, said signaling device being in readiness to be again actuatedupon a second incoming call over the trunk circuit from the automaticexchange, and operator-controlled means for again disabling thesignaling device and for actuating the switching apparatus for thereceiving of a second call While maintaining the original connection ofsaid link circuit with said trunk circuit.

In witness whereof, I hereunto subscribe my name this 3rd day ofDecember A. D., 1919.

CHARLES W. KECKLER.

